The present invention generally relates to trailer hitches of the type commonly used to connect a tractor vehicle to a trailer vehicle and, more particularly, to a hitch assembly providing a means for easily adjusting the position of the ball hitch with respect to the hitch receiver for simplified connection, removal, and towing.
Trailer hitches are devices that connect a tractor vehicle (also called a tow vehicle) to a trailer vehicle by means of a ball hitch which is mounted onto the vehicle, or onto a tow bar which is connected to the vehicle. The hitch ball then mates with a socket located on the trailer tongue. This ball and socket configuration is designed to allow adequate rotation of the socket with respect to the ball so that the vehicle-trailer combination can maneuver around corners. Typically the socket mechanism has a releasably lockable coupling so that it locks onto the ball hitch to prevent decoupling while towing.
Oftentimes the hitch assembly is removable from the vehicle when it is not in use in order to prevent both exposure to the elements and damage to the tow vehicle (or other vehicles) because the operator can easily forget about the protruding presence of the draw bar when a trailer is not being towed. These assemblies usually have a ball hitch which is mounted onto a drawbar which is, in turn, connected to a hitch bar. The hitch bar mates with a hitch receiver which is mounted onto the bumper or another structurally-sound member of the tow vehicle. The hitch bar is designed to be removable from the hitch receiver for times when the vehicle is not towing a trailer.
A common problem with hitches is that the vehicle and the trailer are not often naturally in a convenient vertical position with respect to one another to make their connection, or removal, an easy task. The tow bar of the trailer may be resting below the vertical plane of the hitch ball so that the trailer must first be jacked up to allow the hitch ball to be positioned underneath the tow bar. Many tow bars come fitted with integral jacks to accomplish this. However, if one forgets to raise the jack out of the way before driving, the jack, and possibly the trailer or tow vehicle, can be damaged. Another problem, and one that the integral jack does not address, is that the height of the hitch ball may not be correct for the existing load distribution in the trailer, making the towing operation unsafe or causing excessive wear on the tires. Some hitches have no means of adjusting the vertical position of the hitch ball while other mechanisms are very time consuming to adjust because they require changing the hitch bar which can only be done while the trailer is not connected to the vehicle.
With the purpose of overcoming these problems, several types of adjustable hitches, which present schemes for simplifying the adjustment of the hitch ball relative to the hitch receiver, have been invented. For example, U.S. Pat. No. 3,035,856 issued May 22, 1962 to Mleczko and Grimh shows a load leveler adjustable trailer hitch bar which is constructed to attach to the tow bar of the trailer and allow adjustment of the vertical position of the trailer tongue by rotating a lever on the top of the device. This turns a threaded screw which causes the trailer tongue to move up or down depending on the direction of rotation. The device requires some modification be made to a conventional trailer tongue for it to be installed and functional.
U.S. Pat. No. 3,554,578 issued Jan. 12, 1971 to Reed shows an adjustable trailer hitch which is connected to the rear of a tow vehicle and which allows for vertical adjustment of the hitch ball position by rotating a screw with a motor. The portion of the device including the hitch ball is supported by a pair of guide rods which transfer the trailer loads to the tow vehicle. This device requires that the vehicle be modified or that a mounting plate be installed onto the vehicle for attachment of the hitch. Furthermore, failure of the motor or the electrical power supply would render the device inoperative.
U.S. Pat. No. 4,103,928 issued Aug. 1, 1978 to Sheppard describes an adjustable trailer hitch with interchangeable connecting means. The invention is mounted onto the tow vehicle by way of bolting to a bumper or fastening onto a rear vertical surface. The height of the hitch ball is adjustable, again by means of a rotating screw drive. The device also includes a hitch ball with a locking pin which allows for replacement of the hitch ball without the need for a wrench or other tool. In this invention, the hitch ball and draw bar are attached to a plate which rides in grooves positioned in the portion which is fastened to the bumper.
While the above-described structures teach the use of adjustable hitches for towing applications, there remains a need for improved adjustable hitch assemblies. This need manifests in both the need for simplified structures as well as structures that can be manufactured efficiently at a reduced cost. The present invention is directed to providing an improved construction for adjustable hitch systems.
It is the object of the present invention to provide for a new and useful hitch assembly where the relative height of the draw bar with respect to the hitch bar is easily adjustable.
It is another object of the present invention to provide a new and useful adjustable hitch assembly which mates with standard hitch receivers and hitch balls such that the relative height of the hitch ball may be varied during use.
A further object of the present invention is to provide an adjustable hitch assembly that is easy to manufacture yet which is durable in use.
Still a further object of the present invention is to provide an adjustable hitch assembly that is constructed in such manner as to give enhanced strength and stability during a towing operation.
Yet another object of the present invention is to provide a compact adjustable hitch assembly that has an increased range of height adjustment by its ability to be mounted in alternative orientations.
According to the present invention, then, an adjustable hitch assembly is provided. The adjustable hitch assembly generally includes an elongated housing having an elongated interior with a threaded shaft, such as a worm gear, extending longitudinally within the interior of the housing. A coupling member is threadably received on the shaft for longitudinal movement when the shaft is rotated. At least one end of the shaft is connected to a drive element which resides outside of the housing and which can be used to turn the shaft. The assembly also includes a carriage member, located exteriorly of the housing, with the carriage member being secured to the coupling member for movement therewith. The assembly includes a first member that is affixed to the housing and which is adapted to connect to one of the trailer or tractor vehicles. The assembly also includes a second member that is affixed to the carriage member and which is adapted to connect to the other of the trailer or tractor vehicles.
In one embodiment, the carriage member is secured to the coupling member at at least two laterally spaced locations. The housing may include a flat exterior surface with a pair of longitudinal slots such that the carriage member is connected to the coupling member with fasteners passing through the slots. The carriage member may also include a flat slide portion that confronts the slide face for sliding movement during the advancement of the coupling member along the shaft. The carriage member may also be configured as a yoke with arm portions which confront flat slide surfaces on the housing for advancement along the shaft. The housing may include slots along opposite sides through which the yoke is connected to the coupling member with fasteners. The housing has a surrounding side wall where its interior cross-section may be of a selected shape such that the coupling member has a close-fitting engagement with it during the coupling member""s advancement along the shaft.
The second member may be affixed to the carriage member at an offset location relative to the center of the longitudinal dimension of the carriage member. The first member may be a hitch bar and the second member may be a draw bar or, conversely, the first member may be a draw bar and the second member may be a hitch bar. The hitch bar may be obliquely oriented with respect to the housing. The hitch bar is configured to mate with a hitch receiver and the draw bar may be configured to include a hitch ball.
The invention may also include structures as described above in combination with a hitch receiver. A hitch ball may also be provided with the hitch ball being releasably securable to the draw bar.
These and other objects of the present invention will become more readily appreciated and understood from a consideration of the following detailed description of the exemplary embodiments of the present invention when taken together with the accompanying drawings, in which: